ASTM B848-15

Standard Specification for Powder Forged (PF) Ferrous Materials

Fecha:

2016-12-27 /Active

Abstract:

This specification covers the powder forged ferrous materials fabricated by hot densification of atomized prealloyed or iron powders and intended for use as structural parts. The strcutural parts shall be made by hot forging of powder metallurgy preforms in confined dies with or without subsequent heat treatment. The materials shall conform to the required chemical composition for nickel, molybdenum, manganese, copper, chromium, sulfur, silicon, phosphorus, carbon, and oxygen. The mechanical properties such as yield strength, elongation, Rockwell hardness, impact energy, compressive yield strength and fatigue shal be determined using the tensile test method, Charpy V-notch impact energy test method, and hardness test method. The materials shall conform to the required surface finger oxide penetration, interparticle oxide networks, decarburization depth, and nonmetallic inclusion level.

Scope:

1.1 This specification covers powder forged ferrous materials fabricated by hot densification of atomized prealloyed or iron powders and intended for use as structural parts.

1.2 This specification covers powder forged parts made from the following materials:

1.2.1 Compositions:

1.2.1.1 PF-10XX Carbon Steel (produced from atomized iron powder and graphite powder),

1.2.1.2 PF-10CXX Copper-Carbon Steel (produced from atomized iron powder, copper and graphite powders),

1.2.1.3 PF-11XX Carbon Steel with manganese sulfide for enhanced machinability (produced from atomized iron powder, manganese sulfide, and graphite powders),

1.2.1.4 PF-11CXX, PF-1130CXX, and PF-1135CXX Copper-Carbon Steels with manganese sulfide for enhanced machinability (produced from atomized iron powder, copper, manganese sulfide, and graphite powders),

1.2.1.5 PF-42XX Nickel-Molybdenum Steel (produced from prealloyed atomized iron-nickel-molybdenum powder and graphite powder),

1.2.1.6 PF-46XX Nickel-Molybdenum Steel (produced from prealloyed atomized iron-nickel-molybdenum powder and graphite powder),

1.2.1.7 PF-44XX Molybdenum Steel (produced from prealloyed atomized iron-molybdenum powder and graphite powder), and

1.2.1.8 PF-49XX Molybdenum Steel (produced from prealloyed atomized iron-molybdenum powder and graphite powder).

Note 1: Alloy composition designations are modifications of the AISI-SAE nomenclature. For example: 10CXX designates a plain carbon steel containing copper and XX amount of carbon. Compositional limits of alloy and impurity elements may be different from the AISI-SAE limits. Chemical composition limits are specified in Section 6.

Note 2: XX designates the forged carbon content, in hundredths of a percent, that is specified by the purchaser for the application. For a given specified carbon content, the permissible limits shall be as specified in 6.2.

Note 3: The old acronym for powder forging P/F has been replaced by PF throughout the document. The change in the prefix for the material designations is just to match the currently approved acronym for powder forging. No change has been made to the material specification and performance characteristics for the various powder forged materials.

1.2.2 Grades:

1.2.2.1 Grade A—Density equivalent to a maximum of 0.5 % porosity. The minimum density of those sections of the powder forged part so designated by the applicable part drawing shall not be less than the value specified in Table 1.

(A) Quench-hardening and tempering will reduce the density values. Normalized samples may have lower density values then fully annealed materials.

(B) For the purpose of determining conformance with this specification, measured values shall be rounded “to the nearest unit” in the last right-hand digit used in expressing the specification limit, in accordance with the rounding-off method of Practice E29.

(C) Based on the method described in Smith, D. W., “Calculation of the Pore-Free Density of PM Steels: Role of Microstructure and Composition,” The International Journal of Powder Metallurgy, Vol 28, No. 3, 1992, p. 259. Calculations based on 350 ppm max oxygen content and all oxygen combined as 3MnO · Al₂O₃ · 3SiO ₂.

(D) The method described by Smith is not considered applicable to steels with admixed copper additions. Pore-free densities for these materials were determined by experiment.

1.2.2.2 Grade B—Density equivalent to a maximum of 1.5 % porosity. The minimum density of those sections of the powder forged part so designated by the applicable part drawing shall not be less than the value specified in Table 1.

1.3 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.

Keywords:

powder forged (PF) parts; powder forged (PF) steels; powder forging (PF);

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